1. Field of the Invention
The invention relates to optical plug connectors, in particular for modular electronic devices. Such devices usually have a plurality of printed circuit board plug-in units which are aligned essentially in parallel and are supported by a common motherboard or a so-called backplane. The printed circuit board plug-in units are provided with multiple plug connectors to lead them through the walls and to connect to other printed circuit board plug-in units. Corresponding connection partners are arranged on the rear of the backplane which may be plug connectors of similar design and which can be plugged into an intermediate component arranged in the rear wall, thereby aligning the connection partners.
The invention relates to an optical plug connector which is suitable for this purpose and which, with an attendant alignment of at least one optical wave guide plug, can be inserted into a connecting element, having a holder in which the optical wave guide plug is mounted so as to be axially displaceable counter to the force of a spring element.
Optical connections make extremely high demands in terms of the reproducibility and precision of their efficiency of connection. In contrast to purely electrical plug-type connections, in the case of optical plug-type connections a defined plug-in depth or plug-indepth of the plug connectors and/or a direct physical contact between the connecting end faces of the optical wave guide plugs with the respective connection partner is required. In this context, diverse designs have become known in which a spring force exerts a defined contact pressure between the end faces of the connection partners.
2. Description of the Related Art
International publication WO 94/24594 describes a single-duct optical wall bushing in which two optical wave guide plugs which are mounted so as to be axially displaceable counter to a spring force, each in a plug connector, can be inserted into a centering sleeve of a connection element which penetrates the wall. Locking elements of the connection element engage directly on the holder when the plug connector is inserted and can be unlocked as required by means of an axially displaceable unlocking sleeve (push-pull principle) surrounding the holder.
European patent application EP-0 330 231 A2 describes a wall bushing with two plug connectors each in the form of a hybrid or multipoint connector which has optical and electrical plug pins in addition to centering elements.
A plug connector of the type described above has become known heretofore from European patent EP-0 485 196 B1. There, a connection element penetrates a wall and a plug connector is insertible into the connection element on each side. Each plug connector comprises an optical wave guide plug (so-called multiple fiber ferrule) which receives a plurality of optical wave guide ends arranged in one plane. The optical wave guide plugs can be aligned with respect to one another by means of corresponding centering ducts in the connection element, the optical wave guide plugs which can be pushed back axially counter to the force of a spring element coming into physical contact with the connecting end faces.
The aforethe known plug connectors share the common problem that the maximum plug-in depth of the optical wave guide plugs is defined by the prescribed available spring compression travel of the optical wave guide plug and the stop or locked position of the plug connector is defined. The configuration of the plug connectors must be precisely matched in advance to the respective plug-in depth or wall thickness, because otherwise the desired physical contact between the connecting end faces may not (or no longer) come about.